The devices described below relate to power supplies intended to supply electrical power to medical instruments.
Many electrical surgical devices are provided in the form of electrical surgical tools, such as a thermal cautery device, which can be plugged into a separate power supply. Typically, the power supplied to the electrical surgical tool must be carefully controlled; thus, the power supply includes circuitry to convert available AC power to AC, RF, or DC power at the desired output power levels or frequencies. For example, Herzon, Thermal Cautery Surgical Forceps, U.S. Pat. No. 6,235,027 (May 22, 2001), shows thermal cautery forceps using a power supply to deliver a regulated current to the resistive heating elements in the forceps. Our own cautery instruments, such as the Starion(copyright) Thermal Cautery Forceps, which comprise forceps with resistive heating elements disposed on the grasping tips, are designed to work with our PowerPack Surgical Power Supply. Currently marketed versions of this power supply provide a current to the resistive heating elements depending on the heat load and temperature of the resistive heating device. In addition to these two devices, many electrical surgical instruments are currently marketed to address a variety of surgical techniques and the number of surgical instruments available has been growing.
The increase in the variety of surgical instruments has introduced a problem in medical-grade power supplies. Most power supplies can operate with different kinds of medical instruments, as long as an electrical connection can be established between the power supply and the instrument. However, a medical device manufactured by one company may perform slightly differently than expected when the medical device is used in conjunction with a power supply from another company. Since many medical procedures require precise control of the electrical properties of the medical device, a surgeon or doctor may unintentionally harm a patient when the surgeon uses a power supply and a medical device from different manufacturers. For example, though the Starion(copyright) PowerPack provides optimal power to the various Starion(copyright) electrical surgical tools for which it is intended, the use of connectors available to other medical device manufacturers may permit use of non-Starion(copyright) electrical surgical tools with the PowerPack. When used in combination with such third party electrical surgical tools, it is not possible to ensure that the optimal amount of power is delivered to the tool. Thus, the tool may not function as desired, with the result that the patient may be harmed. Thus, a medical-grade power supply is needed which operates only with the instruments made by that manufacturer and tested with that model of power supply.
The methods and devices described below relate to a power supply that identifies an electrical surgical tool, such as a thermal cautery device, and provides power only to electrical surgical tools that are identified by the power supply. The power supply uses a device identification circuit and a constant current circuit to control the power output to an electrical surgical tool. The device identification circuit identifies whether an electrical surgical tool is designed to be used with that power supply. If the device identification circuit recognizes the electrical surgical tool, then the constant current circuit will provide a constant current, or electrical power, to the tool. In addition, the constant current circuit will provide the tool with the amount of power required by that particular device. If the device identification circuit does not recognize the device connected to the power supply, then the constant current circuit provides no power to the device.